Performance Analysis and Simulation of Maximum Ratio Combining in Underwater Laser Communication

HU Siqi1,2 ZHOU Tianhua1 CHEN Weibiao1

(1.Key Laboratory of Space Laser Communication and Detection Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China 201800)
(2.University of Chinese Academy of Sciences, Beijing, China 100049)

【Abstract】Due to the influence of absorption and scattering of seawater, the amplitude of received signal reduces and the signal-to-noise ratio (SNR) reduces during long distance underwater communications, which leads to the bit error rate (BER) of underwater laser communication systems rise, and eventually limits the distance of communication. For this reason, the maximum ratio combining (MRC) diversity reception technology applied in the underwater laser communication system is put forward. The improvement of MRC spatial diversity reception technology compared with the equal gain combining (EGC) spatial diversity reception technology is analyzed under the influence of absorption and scattering of water. Weighting coefficient distribution of MRC is deduced. The relationship between receiver number and system BER performance is analyzed. Monte Carlo method is used to simulate the performance improvement of MRC based on 532 nm laser at the transmission distance of 100 min Jerlov IB water with six receivers. In the IB and II type water, the relationship between BER and transmission distance is given for MRC and EGC. The theoretical analysis and simulation results show that MRC can distribute gain coefficients more reasonably according to SNR in each receiving branch, to achieve the optimal SNR. Under the requirement of the same BER, MRC can realize the longest transmission distance of underwater laser communication. Under the requirement of the same transmission distance, MRC can reduce BER of communication system. An engineering solution for long-distance underwater laser communication system is provided.

【Keywords】 optical communications; underwater laser communication; maximum ratio combining; Monte Carlo method;


【Funds】 National High Technology Research and Development Program of China (863 Program) (2014AA093301) Defense Innovation Fund of Chinese Academy of Sciences

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    1 Lanzagorta M. Underwater communication. Synthesis Lectures on Communications, 2012, 5 (2): 1–129.

    2 Wang Wenpeng.The analysis of channel characteristics in the underwater laser communication [D]. Qingdao: Ocean University of China, 2014 (in Chinese).

    3 Hu Xiuhan, Hu Siqi, Zhou Tianhua, et al. Rapid estimation of the maximum communication distance for an underwater laser communication system [J]. Chinese J Lasers, 2015, 42 (8) : 0805007 (in Chinese).

    4 Li Xiaochuan. Blue and green laser scattering properties and depolarization in seawater [D]. Chengdu: University of Electronic Science and Technology of China, 2006 (in Chinese).

    5 Li Jinwei, Bi Weihong, Ren Yanhui. A method for simulating time-domain broadening of laser pulse in the underwater laser communication [J]. Optical Technique, 2012, 38 (5): 569–572 (in Chinese).

    6 Wei Liying. PPM modulating of space optical communication [D]. Changchun: Changchun University of Science and Technology, 2007 (in Chinese).

    7 Wang Jun.Research on high-speed, high-sensitivity and width band receiver technology of atmospheric laser communication system [D]. Changchun: Changchun University of Science and Technology, 2012 (in Chinese).

    8 Zhang Huiying, Li Hongzuo, Xiao Dongya, et al. Performance analysis of spatial-diversity reception over combined effects of atmospheric turbulence [J]. Chinese J Lasers, 2016, 43 (4) : 0405002 (in Chinese).

    9 Hu xiuhuan, Zhou Tianhua, He Yan, et al. Chinese Lasers, 2013, 40 (3): 0305003 (in Chinese).

    10 Li Zhaoxun, Dou Dongdong, Ren Xiukun, et al. Performance analysis of equal gain combining receiving system in doubleRayleigh fading [J]. Journal of Information Engineering University, 2011, 12 (1): 37–42.

    11 Hu Xiuhan. University of Chinese Academy of Sciences, 2015 (in Chinese).

    12 Wang Yi, Da Xinyu, Li Yanhua. Ship Electronic Engineering, 2008,28 (2): 70–73 (in Chinese).

    13 Li Jing. Huazhong University of Science and Technology, 2013 (in Chinese).

    14 Jerlov N G. Marineoptics. Amsterdam: Elsevier, 1976.

    15 Gabriel C, Khalighi M A, ourennane S, et al. Monte-carlo-based channel characterization for underwater optical communication systems. Journal of optical Communications and Networking, 2013,5 (1): 1–12.

This Article


CN: 31-1339/TN

Vol 43, No. 12, Pages 207-214

December 2016


Article Outline


  • 1 Introduction
  • 2 Space Diversity Reception Theory and System Model
  • 3 Monte Carlo Simulation on Underwater Channel
  • 4 Conclusion
  • References